This proposed research has two major goals: I. to improve identification of drug abuse in diverse populations, so as to aid in more appropriately specialized treatment planning; and 2. to improve evaluation of drug abuse treatment efficacy with patients differing in co-occurring psychiatric disorders, and differing in gender and ethnicity. Concluding that assessment of drug abuse as a discrete diagnosable disorder belies significant obstacles to reliable and valid identification and treatment, this proposal seeks to produce a differentiated family of scales of identify drug abuse among dually diagnosed individuals (i.e., those with co-occurring serious mental illness) with and without a co-morbid Post- traumatic Stress Disorder (PTSD). This research build upon a formidable base: The newly-revised and renormed MMPI-2 will be used to empirically derive scales to measure presence/absence of drug abuse in the context of (a) presence/absence of co-morbid PTSD; (b)presence/absence of other Axis disorders, such as schizophrenia or major mood disorder; (c) gender; and (d) ethnicity (white/minority). At least 480 treatment-seeking individuals with be diagnosed using CAMMI guidelines (Comprehensive Assessment Multimethod, Multisource Information) for research diagnosis, to yield 15 subjects in 32 cells (drug abuse status x PTSD x co-occurring Axis I status X Gender X Ethnicity). With CAMMI-derived Index diagnoses, MMPI-2 drug abuse scales are then differentiated, based on criterion group distinction methods. The results will enhance efficacy of drug abuse treatment in three ways: l. through more valid, more refined identification of individuals with drug abuse; 2. through provision of an empirical base for assigning individual to more specialized drug abuse treatment programs; and 3. through development of MMPI-2 scales sensitive to variations in treatment, gender, and ethnicity. Revision of the MMPI-2 render it an especially attractive assessment tool, particularly for "matching" studies and measures of treatment process and outcome.